1. Field of the Invention
The present invention relates to a process for preparing a carbon product by using a coal type acicular coke. More particularly, it relates to a process for preparing a carbon product having excellent thermal shock resistance.
2. Description of the Prior Arts
Acicular cokes used for various carbon products have been produced by using petroleum type sources. Recently, various processes for producing acicular cokes by using coal type oils have been proposed.
The carbon products have been used as graphite electrodes, carbon brushes, carbon products of machines, electrode plates and substrates for chemical plants in various industrial fields. Recently, high quality of the carbon products has been required and various characteristics such as electrical, mechanical and thermal charactertistics of the carbon products have been improved to obtain high quality carbon products because of developments and rationalizations of technology.
For example, in a preparation of artificial graphite electrodes for steel productions, certain ultra-high power operation has been employed because of the rationalization by steel makers. As a result, it has been required to use a graphite electrode having excellent thermal shock resistance in high quality. That is, a graphite electrode having excellent characteristics such as great strength and low thermal expansion coefficient, low electric specific resistance and low modulus of elasticity has been required. Various conditions for the preparation of carbon products have been studied to provide satisfactory characteristics. It has been proposed to attain various improvements in steps of preparations of carbon products such as a condition for selecting particle sizes of cokes in blending and a selection of a kind and content of a binder, and a kneading operation, a molding operation, a baking operation, an immersing operation and a graphitizating operation. An improvement of a coke itself for the carbon product has been also studied.
Thus, it has been known that the carbon products prepared by using a coal type acicular coke, have characteristics such as low thermal expansion coefficient and excellent graphitizability, however there has not been found any technology for obtaining a carbon product having satisfactory characteristics for high thermal shock resistance especially high strength.
The inventors have studied, in detail, functions of characteristics of cokes for imparting characteristics of carbon products in order to prepare carbon products having excellent thermal shock resistance by using coal type acicular cokes. As a result, the inventors have found that qualities of carbon products especially thermal shock resistance closely relate to pore volume of the coal type acicular cokes.